The ever recurring growth of fouling organisms on underwater structures such as ships, docks, piers, pilings, fishnets, heat exchangers, dams, piping structures, intake screens, cooling towers and the like is a costly and hazardous problem in both marine and freshwater applications. The presence of fouling organisms such as barnacles, zebra mussels, algae, diatoms, hydroids, bryozoa, ascidians, tubeworms, Asiatic clams and the like causes economic damage in various ways: for example, attachment to the hulls of ships reduces fuel efficiency and causes loss of profitable sailing time because of the need to clean the hulls. Similarly, the attachment of these organisms to cooling water equipment decreases heat conductivity, which eventually reduces or blocks the cooling power of the equipment and drives up costs.
A variety of agents useful for controlling fouling organisms in fresh water or seawater have been used to prevent the attachment and overgrowth of these organisms.
A common method of controlling the presence or attachment of fouling organisms is to coat or permeate the underwater structure with a composition that comprises mixtures of toxic compounds such as tri-n-butyl tin or copper compounds. Antifouling agents in the form of paint can contain up to 60% by weight of the active ingredients and can be used to paint surfaces such as the underwater hull of ships. The paint prevents attachment and growth of fouling organisms by continuously releasing antifouling agents underwater. The disadvantage of many of the present antifouling agents is that they are persistent in the environment, are often acutely toxic and degrade too slowly in aquatic environments and are, therefore, ecologically harmful. Hazardous antifouling agents can eventually bioaccumulate and enter the food chain and therefore represent a threat to marine and human life.
For example, it is well established that heavy metal compounds, especially organotin compounds that are widely used as antifouling agents, accumulate in mussels.
It is an object of this invention to provide an environmentally and ecologically sound method of combating or controlling marine and freshwater fouling organisms.
It is another object of this invention to provide an effective method for protecting aquatic structures against fouling by marine or freshwater fouling organisms.
It is a further object of this invention to provide antifoulant compositions that comprises certain alkylamine derivatives as the active agents. The advantage of these agents is that they are tin and copper free and less toxic to non-target organisms than the existing antifouling compounds. They are also biodegradable so that they are less bioaccumulated and therefore ecologically safer.